Optical constants

Refractive index of AuAl2 (Gold-aluminium intermetallic, Purple plague)

Supansomboon et al. 2008: n,k 0.300–1.32 µm

Data
tabulated nk
Range
0.3–1.32 µm
Points
35
Licence
CC0-1.0

Plot

Click the plot to set the calculator wavelength.

At one wavelength

Range 0.3–1.32 µm
Refractive index n
1.20684
Extinction coefficient k
1.52632
Permittivity ε1
-0.87319
Permittivity ε2
3.68405
Absorption coefficient α
326418 cm⁻¹
Penetration depth δ = λ/(2πk)
61.2712 nm
Abbe number Vd
—
Chromatic dispersion dn/dλ
-1.6 µm⁻¹
Group index ng
2.147
Group velocity dispersion
— fs²/mm
Dispersion parameter D
— ps/(nm·km)
Photon energy
2.11001 eV

ε = (n + ik)², α = 4πk/λ, ng = n − λ dn/dλ, GVD = λ³/(2πc²) d²n/dλ², D = −(λ/c) d²n/dλ². Group-velocity dispersion is given for formula data only.

Use it in Lightsmith

Load this data in Python, simulate in one more line

pip install lightsmith
import lightsmith as ls

# AuAl2 (Gold-aluminium intermetallic, Purple plague): Supansomboon et al. 2008: n,k 0.300–1.32 µm
aual2 = ls.fetch_refractiveindex("other", "AuAl2", "Supansomboon", ref="c5c2f188e848453def5970e347399d653df2ffc2")
print(aual2.range_nm)  # (300, 1320) nm
eps = aual2.eps([633])  # complex permittivity

Downloads the original record once (pinned to the imported snapshot) and caches it.

Lightsmith is open source (MIT): Mie, T-matrix, BEM, DDA, FDTD, RCWA, TMM, mode solvers and inverse design behind one spec, on CPU or GPU. GitHub.

Comments and conditions

68 nm thick AuAl2 film produced by 8 min of sputtering. Room temperature.

References

S. Supansomboon, A. I. Maaroof, M. B. Cortie. "Purple glory": The optical properties and technology of AuAl2 coatings. Gold Bulletin 41, 296-304 (2008)
  • doi:10.1007/bf03214887 “Purple glory”: The optical properties and technology of AuAl2 coatings, Gold Bulletin (2008)

Cite

S. Supansomboon, A. Maaroof and M. B. Cortie. “Purple glory”: The optical properties and technology of AuAl2 coatings. Gold Bulletin, 41, 296-304 (2008), doi:10.1007/bf03214887; Data from the refractiveindex.info database (M. N. Polyanskiy, Sci. Data 11, 94 (2024), doi:10.1038/s41597-023-02898-2)

Data

35 rows as published
AuAl2 (Gold-aluminium intermetallic, Purple plague), Supansomboon et al. 2008: n,k 0.300–1.32 µm: n and k versus wavelength
λ (µm)nk
0.32.0581.499
0.332.0841.722
0.362.0421.863
0.391.8421.872
0.421.6441.785
0.451.431.639
0.481.351.503
0.511.2891.406
0.541.2751.407
0.571.2351.47
0.61.1871.566
0.631.1171.717
0.661.0571.874
0.691.0072.042
0.720.972.21
0.750.9442.372
0.780.932.532
0.810.9212.686
0.840.9142.836
0.870.9072.985
0.90.93.13
0.930.8993.273
0.960.9013.412
0.990.9053.548
1.020.9193.682
1.050.9363.814
1.080.9533.946
1.110.9714.075
1.140.9934.201
1.171.024.325
1.21.0494.446
1.231.0774.562
1.261.1074.676
1.291.1414.789
1.321.1784.898

Optical transmission calculator

Free-standing sample in vacuum, normal incidence
Method
Transmittance T
—
Reflectance R
—

Fresnel reflection calculator

Direction
Rp
—
Rs
—
R = (Rp+Rs)/2
—
Phase φp
—
Phase φs
—
Brewster angle θB
—
Critical angle θC
—